Trying a small modification to the ITMY blends tonight. Because the Z/RZ is suspected to be caused by actuator drive currents, Sheila has allowed me to switch the Z on St1 to a higher blend. If this proves unworkable for arm work tonight, the blend can be switched back easily enough to Tbetter on Z. Getting Ryan's 90mhz blend is possible, but right now would require turning off the Z isolation loop, a bunch of extra clicks( switch each of the individual current blends), then turning the loop back on.

I'm attaching some data that prompted the change. Fabrice made a script last week that plots the coherence of the ISI St1 T240's to the Oplev signals. I messed with it this morning a little to look at all degrees of freedom, shown in the attached plots. The first 2 pages show ISI to oplev pitch, the last 2 are ISI to oplev yaw, from Sunday night, with ITMY in our new <a href="https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=14284">"standard configuration"</a>. Basically, red means high coherence, meaning the ISI is strongly coupled to the motion the oplev is seeing, or something. We think that Z isolation is not strongly coupled to optic motion, so reducing isolation there won't negatively affect the optic. But, reducing the amount of drive on Z, I hope, will reduce the amount of RZ/yaw that is induced.